Misalignment detection apparatus and method

ABSTRACT

A rail misalignment detection system for use in verifying whether fixed span and moveable span rails on a fixed span and a moveable span of a rail bridge, extend within an acceptable range of misalignment when the moveable span is positioned in a closed alignment with respect to the fixed span of the bridge, comprises an optical beam transmitter and a receiver, one mounted on the fixed span and the other mounted on the moveable span, such that the transmitter directs a beam of collimated light to a photocell in the transmitter. The transmitter and receiver are mounted on the respective spans of the bridge such that their position relative to one another corresponds to the relative position or alignment of one set of the rails on the moveable span and fixed span of the bridge. The transmitter and receiver are further positioned relative to one another such that when the rails on the fixed and moveable spans extend within the acceptable range of misalignment the beam from the transmitter strikes the photocell to a sufficient degree to activate the photocell, and when the rails extend beyond the acceptable range of misalignment the beam does not strike the photocell to a sufficient degree to activate the photocell.

BACKGROUND OF THE INVENTION

The present invention relates to an alignment verification system and inparticular to a system for verifying that rails extending across a fixedspan and movable span of a movable span railroad bridge are within anacceptable degree of misalignment.

Proper alignment of a moveable span with a fixed span of a moveable spanrailroad bridge, such as a swing span bridge or draw bridge, isimportant for railroad safety. Excessive misalignment of the rails onthe moveable span with the rails on the fixed span as the train advancesthereacross, could result in derailment of the train or excessive wearon the rails. Current federal railroad administration rules specify thattrains should not be permitted to cross moveable span bridges if therails on the moveable span are not aligned with the rails on the fixedspan within 3/8 of an inch.

Mechanical systems have been developed for verifying that the moveablespan has returned to a closed position in general alignment with thefixed span before permitting trains to pass thereacross. One such systemis disclosed in U.S. Pat. No. 5,186,421. Such systems typically onlydetect misalignment in one plane, either vertically or horizontally.Further, existing systems do not permit relatively precise verificationthat the rails are within a fairly narrow range of misalignment. Onelimiting factor on the development of mechanical systems which might becapable of verifying whether the rails are within a narrow range ofmisalignment, is the severe pounding and vibration on the rails as atrain passes thereacross. It is unlikely that a mechanical systemmounted to the rails and adapted to measure or verify a relativelynarrow range of misalignment could withstand the vibration or poundinggenerated by a train and remain effective.

There remains a need for a reliable system for verifying that the railsof a movable span of a moveable span bridge are within a relativelynarrow range of misalignment with the rails of a fixed span thereofwhich can be used to control the travel of trains thereacross.

SUMMARY OF THE INVENTION

The present invention comprises a rail misalignment detection system foruse in verifying whether first and second rails, one on a fixed span andone on a moveable span of a rail bridge, extend within an acceptablerange of misalignment when the moveable span is positioned in a closedalignment with respect to the fixed span of the bridge. The detectionsystem generally comprises an optical beam transmitter and a receiver,one mounted on the fixed span and the other mounted on the moveablespan, such that the transmitter directs a beam of collimated light to aphotocell in the receiver. The transmitter and receiver are mounted onthe respective spans of the bridge such that their position relative toone another corresponds to the relative position or alignment of one setof the rails on the moveable span and fixed span of the bridge. Thetransmitter and receiver are further positioned relative to one anothersuch that when the rails on the fixed and moveable spans extend withinthe acceptable range of misalignment the beam from the transmitterstrikes the photocell to a sufficient degree to activate the photocell,and when the rails extend beyond the acceptable range of misalignmentthe beam does not strike the photocell to a sufficient degree toactivate the photocell. The photocell communicates with a controllerthat can be programmed to send appropriate signals or otherwise controlthe advancement of trains across the bridge.

The degree and direction of misalignment which will result indeactivation of the photocell is controlled by varying the size andshape of apertures extending through first and second aperture platesmounted in front of the transmitter and receiver respectively. Ahorizontal rectangular slot formed in the aperture plate in front of thereceiver may be used to verify vertical misalignment, while a verticalrectangular slot formed in the aperture plate in front of the receivermay be used to verify horizontal misalignment, and a circular aperturein the aperture plate in front of the receiver may be used to verifymisalignment in any direction about a center axis.

The transmitter and receiver are secured to the respective spans onadjustable mounts which permit adjustment to the vertical and horizontalalignment of the transmitter and receiver relative to the spans to whichthey are attached and to each other. At the time of installation of thetransmitter and receiver, the mounts are adjusted to place thetransmitter and receiver at the same degree of existing misalignment asthe rails using a special gauge.

The gauge generally comprises an elongate bar having a clamping basesecured to a first end thereof for removably securing the elongate barto one of the rails and preferably the rail on the span to which thetransmitter is secured. The elongate bar is secured to that rail suchthat it extends in parallel alignment with the rail to which it isattached and a second end of the elongate bar extends adjacent to therail on the other span.

A laser, such as incorporated in a laser level, is removably mounted tothe elongate bar so as to direct a beam of light toward the second endof the elongate bar. A target holder is slidably mounted to the secondend of the elongate bar for horizontal and vertical movement therewith.The target holder includes an inner surface engaging edge and an uppersurface engaging edge. The relative position of the target holder on thesecond end of the elongate bar is adjusted until the inner surfaceengaging edge abuts against an inner surface of the rail adjacentthereto and the upper surface engaging edge abuts against an uppersurface of the rail.

A target, having a target face with a bull's-eye thereon, is removablysecurable to the target holder. The gauge is sized and the bull's-eye ispositioned on the target face such that the beam from the laser isaligned with the bull's-eye when the inner and upper surface engagingedges of the target holder are positioned in abutting relationship withthe inner and upper surfaces respectively of the second rail and thefirst and second rails are in vertical and horizontal alignment.

If the first and second rails are not in vertical and horizontalalignment when the inner and upper surface engaging edges of the targetholder are positioned in abutting relationship with the inner and uppersurfaces respectively of the second rail, the beam will be displacedfrom the target a distance and direction corresponding to the distanceand direction of misalignment of the first and second rails. A marker isprovided and selectively positionable relative to the target face toindicate where the beam of light from the laser strikes the target face.

After the marker is positioned to record the degree and distance ofmisalignment of the rails, the target is removed from the target holderand placed on the receiver and the laser is removed from the elongatebar and placed on the transmitter. The relative positions of thetransmitter and receiver are adjusted using the adjustable mounts, untilthe laser beam is aligned with the marker on the target face. Thetransmitter and receiver are then mounted in the same relative positionor degree of misalignment as the first and second rails.

OBJECTS AND ADVANTAGES OF THE INVENTION

Therefore, the objects and advantages of the present invention include:to provide an apparatus for verifying relatively narrow ranges oftolerable misalignment between rails on movable and fixed spans of arailroad bridge; to provide such an apparatus which may be remotelymounted relative to the rails on the fixed and moveable spans; toprovide such an apparatus which can provide a signal to indicate whetherthe rails are within an acceptable degree of misalignment; to providesuch an apparatus which is relatively reliable; to provide such anapparatus which is relatively easy to maintain and to provide such anapparatus which is relatively inexpensive.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view in simplified form of a fixed span anda moveable span of a rail bridge shown in a closed orientation andshowing a transmitter mounted to the fixed span on an adjustable mount,a receiver mounted to the moveable span on an adjustable mount and arail misalignment gauge mounted to a set of aligned rails on the fixedspan and moveable span.

FIG. 2 is a top plan view of the rail bridge as shown in FIG. 1.

FIG. 3 is an enlarged and exploded perspective view of a portion of theadjustable mount for the transmitter as shown in FIG. 1 wherein theorientation of the adjustable mount in FIG. 3 is reversed relative toFIG. 1.

FIG. 4 is an enlarged, fragmentary, partially schematic, cross-sectionalview taken generally along line 4--4 of FIG. 3 showing the transmittersecured to the associated adjustable mount.

FIG. 5 is a schematic and fragmentary cross-sectional view of thereceiver.

FIG. 6 is an enlarged and fragmentary cross-sectional view takengenerally along line 6--6 of FIG. 1 showing a clamping base of the railmisalignment gauge secured to a rail on the fixed span of the bridge.

FIG. 7 is an enlarged and fragmentary cross-sectional view takengenerally along line 7--7 of FIG. 1 showing a target holder and targetof the rail misalignment gauge secured to a rail on the moveable span ofthe bridge.

FIG. 8 is an enlarged, fragmentary and partially exploded perspectiveview showing details of the target holder and target of the railmisalignment gauge secured thereto.

FIG. 9 is an enlarged perspective view of the target showing a laserbeam from a laser level of the rail misalignment gauge striking a faceof the target.

FIG. 10 is a fragmentary side elevational view similar to FIG. 1 showingthe laser level supported on the transmitter and the target supported onthe receiver.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

Referring to the drawings in more detail, a simplified representation ofa moveable span railroad bridge 1, of a swing span type, is shown inFIGS. 1 and 2 in a closed position. The moveable span railroad bridge 1comprises a fixed span 2 and a moveable span 3. Rails 4 are mounted ondeck 5 of the fixed span 2 and rails 6 are mounted on the deck 7 of themoveable span 3 respectively. The rails 4 mounted on the fixed span deck5 may be referred to as first or fixed span rails 4, and the rails 6mounted on the moveable span deck 7 may be referred to as second ofmoveable span rails 6.

A gap 10 extends between the fixed span 2 and the moveable span 3 topermit the moveable span 3 to swing away from the fixed span 2 when thebridge 1 is opened to permit barges and the like to pass therethrough.When the bridge 1 is returned to the closed position, such that thefixed span and moveable span rails 4 and 6 are generally aligned, sliderkeys (not shown) slide from a retracted position relative to themoveable span rail 6 across the gap 10 and along the fixed span rail 4on an outer side thereof to span the gap 10 and provide a continuoussurface for the train wheels to travel across.

A transmitter 15 and a receiver 16 are shown mounted to the fixed span 2and moveable span 3 respectively by first and second adjustable mountingassemblies or mounts 17 and 18. It is to be understood that the spans towhich the transmitter 15 and receiver 16 are attached may be reversed.It is to be understood that the transmitter and receiver 15 and 16 andthe mounts 17 and 18 as well other components of the rail misalignmentdetection system as discussed below, are not drawn to scale and onlywith sufficient detail to show their relative positions and generalconfiguration.

First mount 17 is shown in greater detail in FIGS. 3 and 4. Theorientation of first mount 17 in FIGS. 3 and 4 has been reversedrelative to FIG. 1. Second mount 18 is preferably of identicalconstruction as first mount 17. First mount 17 includes angle bracket 21(see FIGS. 1 and 2) and square perimeter frame 22. Angle bracket 21 iswelded or bolted to the side of fixed span deck 5 proximate the gap 10.Perimeter frame 22 is bolted or welded to a vertical leg of anglebracket 21 so as to extend perpendicular to the side of fixed span 2.

First mount 17 includes a vertical adjustment slide 25 which is slidablymounted within a square opening 26 extending between opposed legs ofperimeter frame 22 on vertical adjustment screw 27. Flanges 29 extendoutward from vertical adjustment slide 25 across outer faces of theopposed legs of perimeter frame 22 to stabilize vertical adjustmentslide 25 relative to perimeter frame 22. Vertical clamping plates 30 arebolted on opposite sides of the vertical adjustment slide 25 on the rearthereof and such that a portion of each vertical clamping plate 30extends across a rear face of a respective leg of the perimeter frame22. A vertically extending guide slot 31 is formed in each of theclamping plates 30. A bolt 32 extends through the guide slot 31 in eachclamping plate 30 and into the respective leg of the perimeter frame 22.When a nut 33 on the end of bolt 32 is loosened, the clamping plate 30is free to slide vertically relative to bolt 32. Nuts 33 are tightenedagainst the respective clamping plate 31, to fix the vertical positionof the clamping plate 30 and the vertical adjustment slide 25.

The vertical adjustment screw 27 extends through a bore 34 in thevertical adjustment slide 25 which is of a slightly larger diameter thanthe outer diameter of vertical adjustment screw 27 to permit thevertical adjustment slide 25 to slide freely on screw 27 when theclamping plates 30 are free to slide relative to bolts 32. Two pairs ofnuts or jam nuts 35 threadingly secured on vertical adjustment screw 27on opposite sides of vertical adjustment slide 25, may be advanced awayfrom vertical adjustment slide 25 to permit slide 25 to be slidvertically. After the desired vertical alignment of slide 25 isestablished and the nuts 33 on bolts 32 are tightened against clampingplates 30, nuts 35 are tightened against vertical adjustment slide 25 tofurther fix its vertical alignment.

The adjustable mount 17 further includes a horizontal adjustment slide40 which is slidably mounted in abutting relationship with verticaladjustment slide 25 on horizontal adjustment screw 41. Opposite ends ofhorizontal adjustment screw 41 are bolted onto a front face of verticaladjustment slide 25 on spacers 43 such that the horizontal adjustmentscrew 41 extends horizontally relative to vertical adjustment slide 25and in spaced apart relation thereto. Horizontal adjustment screw 41extends through a bore 45 in wall 46 of the horizontal adjustment slide40. Wall 46 generally extends centrally and vertically relative tohorizontal adjustment slide 40. The bore 45 in horizontal adjustmentslide 40 is of slightly greater diameter than horizontal adjustmentscrew 41 such that the horizontal adjustment slide 40 generally slidesfreely relative to screw 41. Two pairs of nuts or jam nuts 47threadingly secured on horizontal adjustment screw 41 on opposite sidesof horizontal adjustment slide 40, may be advanced away from horizontaladjustment slide 40 to permit slide 40 to be slid horizontally. Afterthe desired horizontal alignment of slide 40 is established, nuts 47 aretightened against horizontal adjustment slide 40 to fix its horizontalalignment.

Horizontal adjustment slide 40 is further secured to vertical adjustmentslide 25 by horizontal guide bolts 48 (one of which is shown partiallyin FIG. 3) extending through horizontal guide slots 50 in verticaladjustment slide 25 and into horizontal adjustment slide 40. Nuts 52(one of which is shown in FIG. 4) on the rear ends of bolts 48 may betightened down against a rear face of vertical adjustment slide 25 toassist in fixing the horizontal alignment of horizontal adjustment slide40.

A cantilever plate 55 is secured at a first end 56 to horizontaladjustment slide 40. In particular, first end 56 of cantilever plate 55is positioned between sidewalls 57 and 58 of horizontal adjustment slide40 and on top of a portion of horizontal adjustment slide 40 extendingbetween sidewalls 57 and 58. A pivot pin 60 extends through a pivot bore61 in the cantilever plate 55 proximate the first end thereof and issecured on opposite ends to sidewalls 57 and 58. A guide pin 63similarly extends through ovate guide slots 64 formed in the side walls57 and 58 and through a second bore 65 in the cantilever plate 55 closerto the first end 56 relative to pivot bore 61. The guide pin 63 issecured on opposite ends to sidewalls 57 and 58. The cantilever plate 55pivots vertically about pivot pin 60. First and second set screws 66 and67 extend generally vertically downward through cantilever plate 55 andengage an upwardly facing surface of the horizontal adjustment slide 40and a third screw 68 extends vertically downward through cantileverplate 55 and into horizontal adjustment slide 40. The screws 66, 67 and68 are adjustable to adjust the pivot position of the cantilever plate55 relative to horizontal adjustment slide 40.

The cantilever plate 55 is sized for mounting of the transmitter 15 orreceiver 16 thereto. A transmitter 15 is shown secured to the cantileverplate 55 in FIGS. 3 and 4. A cable hole 70 is formed in the cantileverplate 55 such that electrical cables may be run therethrough andconnected to the transmitter 15 or receiver 16.

Referring to FIG. 4, the transmitter 15 includes a light emitting diodeor light source 75 secured within a transmitter housing 76 behind atransmitter aperture plate 77. The light source 75 is positionedgenerally centrally behind an aperture 78 in the transmitter apertureplate 77. Referring to FIG. 5 (which generally comprises a schematicview of the receiver 16), the receiver 16 includes a photo cell 80secured within a receiver housing 81 behind a receiver aperture plate 82having a receiver aperature 83 extending therethrough. A mirror 84,positioned in line with and at a 45 degree angle relative to theaperature 83, reflects the light passing through the receiver aperature83 to the photocell 80. It is to be understood that a transmitters orreceivers of a wide range of designs could be utilized in conjunctionwith the rail misalignment detection system of the present invention.

The light source 75 is preferably of the type which produces a beam ofmodulated light. The photo cell 80 is selected to detect light of thewavelength emitted by the light source 75 and at the same modulation asemitted by the light source 75 such that ambient light does not producefalse readings. The photo cell 80 generally comprises a switch which isactivated or changes its condition when it is struck by modulated lightof the detectable wavelength and of sufficient intensity.

The transmitter aperture plate 77 is designed to produce a beam of lightwhich is relatively collimated with a minimal degree of divergence, topermit or facilitate relative accurate sensing by the photo cell 80. Thephrase, collimated beam, generally refers to any beam of radiation whoserays are nearly parallel so that the beam does not converge or divergeappreciably. For the purpose of this application, a beam of collimatedlight shall refer to a beam of light which is sufficiently collimated topermit relatively accurate detection by a photo cell.

In this application the term light generally refers to any wavelength ofelectromagnetic radiation which may be collimated and which may bedetected by a photo cell or its equivalent. Due to cost considerations,the light source 75 of the preferred embodiment, comprises a lightemitting diode that produces a beam of visible light of a redwavelength. Transmitters and receivers utilizing visible light andinfrared light are readily available. It is foreseeable thattransmitters and receivers emitting and detecting electromagneticradiation of other wavelengths might be utilized in conjunction withthis invention if such systems are or become available.

A convex surface 85 is milled into an inner surface 86 of thetransmitter aperture plate 77 around the aperture 78 extendingtherethrough to facilitate the collimation of light emitted from lightsource 75 through deflection of diverging rays of said light away fromsaid aperture 78. The aperture 78 is relatively elongated and theaperture plate 77 is anodized black to reduce internal reflection of thelight passing through aperture 78 to facilitate collimation.

The aperture 78 of transmitter aperture plate 77 and aperture 83 ofreceiver aperture plate 82 are sized and shaped to verify whether thetransmitter 15 and receiver 16 are within an acceptable degree ofdisplacement relative to one another. Aperture 78 may be circular toverify the degree of displacement in any direction relative to trueaxial alignment of the light source 75 relative to photo cell 80. Anaperture 78, generally shaped as a vertically extending slot withparallel edges is used to verify horizontal displacement, while ahorizontally extending slot with parallel edges is used to verifyvertical displacement. An aperture 78 which is rectangular may be usedto verify both vertical and horizontal displacement but within differingacceptable limits.

A cartridge heater (not shown) is secured within a bore in transmitteraperture plate 77 proximate the aperture 78 for use in heating theaperture plate 77 to minimize condensation within the aperture 78 and tofacilitate the evaporation of moisture which might collect within theaperture 78 such as during a rain storm. Water collecting within theaperture 78 may adversely effect the accuracy of the system by changingthe characteristics of the beam of light emitted from the light source75. Similarly, a cartridge heater (not shown) is secured within a borein receiver aperture plate 82 proximate the aperture 83 for use inheating the aperture plate 82 to minimize condensation within theaperture 83 and to facilitate the evaporation of moisture which mightcollect within the aperture 83. It is foreseen that other heat sources,other than cartridge heaters, could be utilized to keep moisture out ofthe apertures 78 and 83, or that other means for doing so might beincorporated therein.

Referring to FIG. 4, the transmitter housing 76 is pivotally mounted toa pivot pin or dowel 92 extending upward from the cantilever plate 55and into a bore 93 of the housing 76. A position locking bolt 94 extendsfrom the housing 76 through an elongate slot 95 in the cantilever plate55 to permit pivoting of the rear of the housing 76 relative to thepivot pin 92. Nut 96 on bolt 94 may be tightened down against thecantilever plate 55 to fix the position of the housing 76 relativethereto.

The transmitter 15 and receiver 16 are mounted relative to an alignedset of the fixed span and moveable span rails 4 and 6 for verifyingwhether the fixed span rail 4 extends within an acceptable range ofmisalignment with the moveable span rail 6. Because the transmitter 15and 16 are mounted remotely from the rails 4 and 6, it is necessary tomake sure that the alignment of the transmitter 15 and receiver 16corresponds to the alignment of the rails 4 and 6. Further, it is to beunderstood that the fixed span and moveable span rails 4 and 6 rarelywill be in perfect alignment to begin with. Therefore, to ensure thatthe transmitter 15 and receiver 16 accurately verify whether the fixedspan and moveable span rails 4 and 6 are within the acceptable range ofmisalignment, the transmitter 15 and receiver 16 are aligned tocorrespond to the same degree of misalignment as the fixed span andmoveable span rails 4 and 6 using gauge 100 shown secured to the rails 4and 6 in FIGS. 1 and 2.

Before using gauge 100 to set the alignment of the transmitter 15 andreceiver 16, the mounts 17 and 18 are adjusted to level the transmitter15 and receiver 16 and place them in general alignment.

The gauge 100 includes a clamping base 101 adapted to be secured to oneof either the fixed span or moveable span rails 4 or 6. The clampingbase 101 is preferably secured to the rail 4 or 6 on the span 3 or 5 onwhich the transmitter 15 is mounted, which in the embodiment disclosedherein is fixed span rail 4. Referring to FIG. 6, the clamping base 101includes a horizontal leg 102 and a vertical leg 103. The horizontal leg102 is adapted to rest on top of the head or ball 104 of the rail towhich it is attached. The vertical leg 103 extends downward from thehorizontal leg 102 along the inner side of the rail. A pair of abutmentposts or fixed jaws 105 (one of which is shown in FIG. 6) are secured toand extend inward from the vertical leg 103 in spaced relation fromhorizontal leg 102 and generally adjacent an inner surface 106 of thehead or ball 104 of rail 4. The inner surface 106 is the surface againstwhich the train wheel flange abuts as a train advances over the rail.Abutment posts 105 are mounted on bolts 107 extending through verticallyoriented slots 108 in vertical leg 103 to permit vertical adjustment ofabutment posts 105 relative to vertical leg 103 to permit the abutmentposts 105 to be positioned against a portion of the inner surface 106 ofrail head 104 which is generally flat. The abutment posts are generallyspaced below the horizontal leg 102 to accommodate or extend around anyprotrusions or lips formed on the rail ball inner surface 106 throughwear thereon.

Movable jaws 109 are slidably mounted relative to horizontal leg 102therebelow and on a side opposite vertical leg 103. Movable jaws 109 areadvanceable into engagement with the rail 4 on a side opposite fixedjaws 105 for drawing the fixed jaws 105 into engagement with the innersurface 106 of ball 104 of rail 4.

An elongate bar 115 is mounted at a first end 116 to the clamping base101, on an upper surface thereof, such that the elongate bar 115 extendsin parallel alignment over the rail 4, across the gap 10, between thefixed span 2 and moveable span 3, and over an end portion of themoveable span rail 6, such that a second end 117 of elongate bar 115extends over rail 6. The clamping base 101 is secured to the rail 4 suchthat elongate bar 115 extends parallel to a vertical plane extendingalong the inner surface 106 of rail head 104 and parallel to ahorizontal plane extending along an upper surface of the rail head 104.A level vial 118 is mounted in the end of the clamping base 101 toverify that the elongate bar 115 generally oriented in true vertical andhorizontal alignment.

A laser, incorporated in a laser level 120 is mounted above the elongatebar 115 on laser mounting bracket 121. The laser level 120 is positionedbetween sidewalls of the laser mounting bracket 121 so as to direct alaser beam toward the second end 117 of the elongate bar 115. Themounting bracket 121 maintains the laser level 120 in parallel alignmentwith a longitudinal axis of the elongate bar 115.

As best seen in FIG. 8, a target holder 125 is slidably mounted to thesecond end 117 of elongate bar 115 on a bolt 127 extending axially outof the second end 117 of elongate bar 115. The target holder 125includes horizontal slide plate 130, vertical slide plate 131 and clampbracket 132. A horizontally extending channel 135 is formed on an innersurface of the horizontal slide plate 130 and is adapted to receive thesecond end 117 of elongate bar 115. A horizontal slot 136 extendsthrough the horizontal slide plate 130 centrally relative to channel 135such that the bolt 127 on the end of elongate bar 115 extends throughhorizontal slot 136 when the horizontal slide plate 130 is mounted onthe second end 117 of elongate bar 115 to permit horizontal sliding ofthe horizontal slide plate 130 relative thereto.

A vertically extending channel 137 is formed on an outer surface of thehorizontal slide plate 130 and is adapted to receive a portion of acentral portion 140 of the vertical slide plate 131 to permit thevertical slide plate 131 to slide vertically relative thereto. A squarehole 141 is formed in and extends through the central portion 140 ofvertical slide plate 131. The vertical slide plate 131 is positionedwithin the vertically extending channel 137 of the horizontal slideplate 130 such that the bolt 127 extends through the square hole 141 topermit the vertical slide plate 131 to move vertically or horizontallyrelative to the second end 117 of the elongate bar 115.

A lower end of the vertical slide plate 131 includes a rail uppersurface engaging edge 143 adapted to be positioned against or supportedon an upper surface of the ball of rail 6 as best seen in FIG. 7. A railside engaging member 145, having a rail inner surface engaging edge 146,is secured to one side of the vertical slide plate 131 such that therail side engaging member 145 extends in spaced apart relation below aportion of the rail upper surface engaging edge 143 thereof. Theposition of the vertical slide plate 131 is slidably adjustablehorizontally relative to the second end 117 of elongate bar 115 toadvance the rail inner surface engaging edge 146 into abuttingrelationship with the inner surface of the ball of rail 6. The rail sideengaging member 145 is spaced below the rail upper surface engaging edge143 to extend around any protrusions or lips formed on an upper portionof the inner surface of the ball of rail 6 due to wear. The rail sideengaging member 145 is mounted on bolts (not shown) secured within slots(not shown) on the vertical slide plate 131 to permit verticaladjustment of the rail side engaging member 145 relative to the verticalslide plate 131.

The clamp bracket 132 has a vertically extending channel 147 formedtherein adapted to slidingly receive a portion of the central portion140 of vertical slide plate 131. A horizontal slot 148 extends throughthe clamp bracket 132 such that the bolt 127 extends therethrough whenthe clamp bracket 132 is positioned against the vertical slide plate131. A grippable knob 149 is secured to the distal end of bolt 127 andcan be tightened against the clamp bracket 132 to press the clampbracket 132, the vertical slide plate 131 and the horizontal slide plate130 against the second end 117 of elongate bar 115 to fix their relativeposition.

The elongate bar 115 is removably securable to the clamping base 101,such that the direction away from the base 101 which the bar 115 extendsmay be reversed to permit the side of the ball 104 to which the jaws 105and 109 abut to be reversed. Similarly the vertical slide plate 131 maybe reversed to reverse the side of the ball 104 against which the sideengaging member 145 abuts.

As best seen in FIG. 8, a notch 150 is formed in an upper portion of thevertical slide plate 131. The notch 150 is adapted to receive a targetmounting arm 151 which extends rearwardly from target 152. The targetmounting arm 151 is removably secured to the vertical slide plate 131 ofthe target holder 125 by a threaded bolt extending through alignedthreaded bores in the target mounting arm 151 and the vertical slideplate 131. Referring to FIG. 9 which is a perspective view of target152, a bulls-eye 155 is formed on a face 156 of the target 152. Whensecured to the target holder 125, the target mounting arm 151 supportsthe target 152 in front of the target holder 125 and generally inalignment with a laser beam 157 emitted from laser level 120.

The components of the gauge 100 are sized such that if the innersurfaces and upper surfaces of the balls of the fixed span rail 4 andmoveable span rail 6 are perfectly aligned the laser beam from laserlevel 120 will be aligned with and strike the bulls-eye 155 on the face156 of the target 152 when the rail upper surface engaging edge 143 oftarget holder 125 is positioned against an upper surface of the ball ofrail 6 and the rail inner surface engaging edge 146 is positionedagainst an inner surface of the ball of rail 6. If the rails 4 and 6 aremisaligned, the laser beam will be displaced from the bulls-eye 155 anequivalent distance both horizontally and vertically.

Referring to FIG. 9, a marker 160 is secured to the target 152 andselectively positionable relative to the target face 156 to indicatewhere the laser beam 157 from laser 120 strikes the target face 156. Themarker 160 comprises a rectangular metal strap 161 having a circularbore 162 extending through one end thereof and an elongate slot 163extending through an opposite end thereof. The strap 161 is pivotallysecured relative to the face 156 of the target 152 by a bolt 165extending through the elongate slot 163 and into a mounting block 166 ontop of the target 152. A knob 167 on bolt 165 can be tightened againstthe strap 161 to fix its orientation relative to the target face 156.The circular bore 162 in strap 161 is sized to generally correspond withthe diameter of the laser beam emitted by laser level 120 to provide avisual indication of where the beam 157 strikes the target face 156. Itis foreseen that other means could be utilized for a marker, such as around sticker, sized to correspond to the diameter of beam 157,removably secureable to the target face 156.

When the rails 4 and 6 are misaligned and the gauge 100 is positionedthereon as discussed above, the laser beam will be offset from thebulls-eye 155 an equivalent distance as the degree of misalignment bothhorizontally and vertically. The knob 167 may be loosened relative tostrap 161 and the strap 161 is maneuvered until the circular bore 162therein is aligned with the laser beam 157. The knob 167 is thentightened to fix the position of the strap 161 and thereby record thedegree of misalignment of the rails 4 and 6.

Once the degree of misalignment is recorded on the target 152, thetarget 152 is removed from the target holder 125 and positioned on thereceiver 16, as generally shown in FIG. 10. In particular, the targetmounting arm 151 is positioned in a similarly sized arm receivingchannel 170 (see FIG. 5) formed in the receiver 16 in an upper surfaceof the housing 81 thereof such that the target 152 generally extends infront of the receiver 16 and the target face 156 faces the transmitter15. The laser level 120 is removed from the gauge 100 and positioned onthe transmitter 15. In particular, the laser level 120 is positioned ina similarly sized laser level receiving channel 171 (see FIGS. 3 and 4)formed in the transmitter 15 in an upper surface of the housing 76thereof such that the laser level 120 directs a laser beam toward thetarget face 156. The relative horizontal and vertical positions of thetransmitter 15 and receiver 16 are then adjusted using the first andsecond adjustable mounts 17 and 18 respectively until the laser beamemitted from laser level 120 is aligned with the circular bore 162 onthe strap 161 of marker 160. The transmitter 15 and receiver 16 arethereby positioned in the same degree or amount of misalignment as therails 4 and 6.

For example, if the inner surfaces of the balls of rails 4 and 6 arealready misaligned by one eighth of an inch horizontally at the time thetransmitter 15 and receiver 16 are installed, the misalignment methodnoted above is used to misalign the transmitter 15 and receiver 16 byone eighth of an inch. Assuming the transmitter 15 and receiver 16 aredesigned to verify misalignment within three eighths of an inch, anyfurther misalignment of the transmitter 15 and receiver 16 in the samedirection horizontally in excess of two eighths or one quarter of aninch will deactivate the photo cell 80 because the beam of collimatedlight emitted from the transmitter 15 will no longer strike the photocell to a sufficient degree. The photo cell 80 is electrically connectedto the signal system for the bridge 1, such that deactivation of thephoto cell 80 changes the output from the system from indicating thatthe bridge 1 is safe to cross to indicating that the bridge is not safeto cross.

Once the transmitter 15 and receiver are misaligned to the same degreeas the rails 4 and 6, the laser level 120 and target 152 are removedtherefrom and covers (not shown) with openings therein for the beam ofcolimated light are preferrably placed over the transmitter 15 andreceiver 16 to protect the transmitter 15 and receiver 16 from theelements.

An electronics package for the rail misalignment detection system, mightincorporate a delayed output turn off to prevent immediate turn off ofthe optical output circuit in case an object, such as an insect or bird,passes in front of the path of the optical beam from the transmitter 16.The electronics package might also include an external relay contactclosure to lengthen the delay time when a train passes over the bridgewhen misalignment of the bridge is at maximum allowable limits toprevent the output from the electronics from turning on and offintermittently due to vibration from the train passing across thebridge. The electronics package also ceases to give output if the bridgemechanical locking sensing circuits, part of the bridge electronicssystem, are not in their normal condition. When an opening of the bridgeis required, a time delay circuit activates with the unlocking process,and at the end of this delay, the optical output circuits are checked tosee that the circuits are indeed off. If any of the optical circuits arein the "on" condition the output control circuits of the electronicspackage is latched off, preventing output drive from activating uponbridge closing. This function is primarily to detect a defective opticalunit which is permanently in the "latched on" condition. The circuit isalso self-restoring in that if the bridge is again unlocked and thenre-locked and the fault is not detected at this time, the circuit willresume normal operation. All of these functions are repeated in anotherparallel circuit and their outputs compared to see if they agree beforethe output control circuit is activated.

In the preferred embodiment discussed above, it was noted that mounts 17and 18 are essentially the same and permit adjustment of the relativeposition of the transmitter 15 and receiver 16 positioned thereon. It isforeseen that for cost considerations it may be preferable that only oneof the mounts is adapted for vertical and horizontal adjustment of thetransmitter or receiver (also referred to as optical units) mountedthereon and the other generally does not readily permit adjustment ofthe relative position of the optical unit positioned thereon.

It is foreseen that one rail misalignment detection system, generallycomprising a transmitter and its mount and a receiver and its mount,will be mounted at each end of a swing span type bridge for each set oftracks. If the bridge includes two sets of tracks a total of four railmisalignment detection systems would be mounted on the bridge.

It is also foreseen that the misalignment detection system could be usedin moveable span bridges other than rail bridges. The misalignmentdetection system would be used to verify that certain fixed span membersand moveable span members remain within a tolerable range ofmisalignment upon closing of the bridge.

It is also foreseen that a source of collimated light other than a laserlevel 120 may be used for the gauge 100.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed is:
 1. A rail misalignment detection system for use inverifying whether a first rail on a moveable span of a rail bridgeextends within an acceptable range of misalignment with a second rail ona fixed span of the rail bridge; said detection system comprising:a) atransmitter mounted on a first of said moveable span and said fixed spanof said rail bridge and positioned to direct a beam of collimated lighttoward said second of said moveable span and said fixed span; b) areceiver mounted on a second of said moveable span and said fixed spanof said rail bridge and including a photo cell; said receiver and saidtransmitter mounted relative to said first and second rails and to eachother such that when said first and second rails extend within theacceptable range of misalignment said beam strikes said photo cell to asufficient degree to activate said photocell, and when said first andsecond rails extend beyond the acceptable range of misalignment saidbeam does not strike said photocell to a sufficient degree to activatesaid photocell; and c) said photocell communicating with a signal systemfor said bridge such that deactivation of said photocell changes anoutput from said signal system from indicating that said bridge is safeto cross to indicating that said bridge is not safe to cross.
 2. Therail misalignment detection system as in claim 1 wherein:(a) said beamof collimated light is of an infrared wavelength.
 3. The railmisalignment detection system as in claim 1 wherein:(a) said beam ofcollimated light is of a visible light wavelength.
 4. The railmisalignment detection system as in claim 1 wherein:(a) said transmitteris mounted on a first mount which is mounted to said first of said fixedspan and said moveable span such that the horizontal and verticalalignment of said transmitter is adjustable; (b) said receiver ismounted on a second mount which is mounted to said second of said fixedspan and said moveable span such that the horizontal and verticalalignment of said receiver is adjustable.
 5. A rail misalignmentdetection system for use in verifying whether a first rail on a moveablespan of a rail bridge extends within an acceptable range of misalignmentwith a second rail on a fixed span of the rail bridge; said detectionsystem comprising:a) a transmitter mounted on a first of said moveablespan and said fixed span of said rail bridge and positioned to direct abeam of collimated light toward said second of said moveable span andsaid fixed span; b) a receiver mounted on a second of said moveable spanand said fixed span of said rail bridge and including a photo cell; saidreceiver and said transmitter mounted relative to said first and secondrails and to each other such that when said first and second railsextend within the acceptable range of misalignment said beam strikessaid photo cell to a sufficient degree to activate said photocell, andwhen said first and second rails extend beyond the acceptable range ofmisalignment said beam does not strike said photocell to a sufficientdegree to activate said photocell; c) said receiver includes a receiveraperture plate mounted in front of said photocell and having a receiveraperture extending therethrough; said receiver aperture sized, shapedand positioned such that said beam of collimated light will not strikesaid photocell to a sufficient degree to activate said photocell unlesssaid first and second rails are within the acceptable range ofmisalignment.
 6. The rail misalignment detection system as in claim 5wherein:c) said transmitter includes a transmitter aperture platemounted in front of a source of a non-collimated beam of light; saidtransmitter aperture plate having a transmitter aperture extendingtherethrough adapted to reduce divergence of said non-collimated beam oflight passing therethrough to produce said beam of collimated light. 7.A gauge for detecting and recording the degree of misalignment between amoveable span rail on a moveable span of a rail bridge with a fixed spanrail on a fixed span of the rail bridge comprising:(a) an elongate bar;(b) a clamping base secured to said elongate bar at a first end thereoffor removably securing said elongate bar to a first of said fixed spanand moveable span rails such that said elongate bar extends in parallelalignment with said rail to which it is attached and a second end ofsaid elongate bar extends adjacent to the second of said rails; (c) afirst source of collimated light removably mounted to said elongate barso as to direct a first beam of collimated light toward a second end ofsaid elongate bar; (d) a target holder having an inner surface engagingedge and an upper surface engaging edge and slidably mounted to saidsecond end of said elongate bar to permit said target holder to slidevertically and horizontally relative to said elongate bar such that saidinner surface engaging edge is slidingly advanceable into abutment withan inner surface of the second of said rails and said upper surfaceengaging edge is slidingly advanceable into abutment with an uppersurface of the second of said rails; (e) a target removably securable tosaid target holder and having a target face with a bulls-eye thereon;said bulls-eye positioned on said target face such that said first beamof collimated light is aligned with said bulls-eye when said inner andupper surface engaging edges of said target holder are positioned inabutting relationship with the inner and upper surfaces respectively ofthe second of said rails and the inner surfaces and upper surfaces ofthe first and second rails are aligned; (f) a marker selectivelypositionable relative to said target face to indicate where said firstbeam of collimated light strikes said target face.
 8. The gauge asdisclosed in claim 7 wherein:(a) said marker comprises a strap having acircular bore formed at one end thereof of a diameter corresponding tothe diameter of the first beam of collimated light striking the targetface, said strap secured to said target such that said circular bore isselectively positionable in alignment with said first beam of collimatedlight.
 9. The gauge as disclosed in claim 7 in combination with a railmisalignment detection system for use in verifying whether a moveablespan rail on a moveable span of a rail bridge extends within anacceptable range of misalignment with a fixed span rail on a fixed spanof the rail bridge; said detection system comprising:(a) a transmittermounted on a first mount on a first of said moveable span and said fixedspan of said rail bridge and directing a second beam of collimated lighttoward said second of said moveable span and said fixed span; (b) areceiver including a photo cell; said receiver mounted on a second mounton a second of said moveable span and said fixed span of said railbridge such that said photocell faces said transmitter; at least one ofsaid first and second mounts being adjustable such that the vertical andhorizontal alignment of said transmitter or said receiver mountedthereon is adjustable; said receiver and said transmitter mountedrelative to said first and second rails and to each other such that whensaid first and second rails extend within the acceptable range ofmisalignment said second beam of collimated light strikes said photocellto a sufficient degree to activate said photocell, and when said firstand second rails extend beyond the acceptable range of misalignment saidsecond beam of collimated light does not strike said photocell to asufficient degree to activate said photocell, (c) said first source ofcollimated light is removably securable to said transmitter and saidtarget is removably securable to said receiver such that adjustment ofthe relative alignment of said transmitter and said receiver to alignsaid first beam of collimated light with said marker on said target faceadvances said transmitter to the same degree of misalignment with saidreceiver as the first rail to the second rail.
 10. The gauge asdisclosed in claim 7 in combination with a rail misalignment detectionsystem for use in verifying whether a moveable span rail on a moveablespan of a rail bridge extends within an acceptable range of misalignmentwith a fixed span rail on a fixed span of the rail bridge; saiddetection system comprising:(a) a transmitter mounted on a firstadjustable mount on a first of said moveable span and said fixed span ofsaid rail bridge such that the vertical and horizontal alignment of saidtransmitter is adjustable; said transmitter directing a second beam ofcollimated light toward said second of said moveable span and said fixedspan; (b) a receiver including a photocell; sad receiver mounted on asecond adjustable mount on a second of said moveable span and said fixedspan of said rail bridge such that the vertical and horizontal alignmentof said receiver is adjustable; said receiver and said transmittermounted relative to said first and second rails and to each other suchthat when said first and second rails extend within the acceptable rangeof misalignment said second beam of collimated light strikes saidphotocell to a sufficient degree to activate said photocell, and whensaid first and second rails extend beyond the acceptable range ofmisalignment said second beam of collimated light does not strike saidphotocell to a sufficient degree to activate said photocell, (c) saidfirst source of collimated light is removably securable to saidtransmitter and said target is removably securable to said receiver suchthat adjustment of the relative alignment of said transmitter and saidreceiver to align said first beam of collimated light with said markeron said target face advances said transmitter to the same degree ofmisalignment with said receiver as the first rail to the second rail.11. A method for verifying whether a first rail on a moveable span of arail bridge extends within an acceptable range of misalignment with asecond rail on a fixed span of the rail bridge; said method comprisingthe steps of:a) attaching a transmitter to a first of said fixed spanand said moveable span remotely relative to said first or second railthereon such that said transmitter emits a first beam of collimatedlight toward a second of said fixed span and said moveable span; b)attaching a receiver to said second of said fixed span and said moveablespan remotely relative to said first or second rail thereon; saidreceiver having a photo cell positioned within a housing behind anaperture extending through said housing; said aperture sized and shapedsuch that said beam of collimated light will strike said photo cell to asufficient degree to activate said photo cell unless said beam ofcollimated light is misaligned relative to said photocell by an amountexceeding the acceptable range of misalignment between said first andsecond rails to be detected; c) measuring the degree of misalignmentbetween the first rail and the second rail; and d) misaligning thetransmitter from the receiver to correspond to the measured degree ofmisalignment between the first and second rail.
 12. The method as inclaim 11 wherein:a) said measuring step includes connecting an elongatebar to said first rail such that a second end of said elongate barextends adjacent said second rail and positioning a laser on saidelongate bar to direct a beam of light toward a target positioned on atarget holder connected to said second end of said elongate bar; saidtarget holder including rail engaging surfaces and being movablerelative to said second end of said elongate bar to advance said railengaging surfaces against a side and a top of said second rail; saidmethod further including marking a spot on said target where said beamof light strikes said target; and b) said misaligning step includesremoving said laser from said elongate bar and placing it on saidtransmitter and removing said target from said target holder andaligning said transmitter relative to said receiver such that said beamof light emitted from said laser is aligned with said spot marked onsaid target.
 13. A misalignment detection system for use in verifyingwhether a moveable span member on a moveable span of a bridge extendswithin an acceptable range of misalignment with a fixed span member on afixed span of the bridge; said detection system comprising:a) atransmitter comprising a first source of collimated light and mounted ona first of said moveable span and said fixed span of said bridge andpositioned to direct a first beam of collimated light toward said secondof said moveable span and said fixed span; b) a receiver mounted on asecond of said moveable span and said fixed span of said bridge andincluding a photo cell; said receiver and said transmitter mountedrelative to said first and second members and to each other such thatwhen said first span and moveable span members extend within theacceptable range of misalignment said first beam strikes said photo cellto a sufficient degree to activate said photocell, and when said fixedspan and moveable members extend beyond the acceptable range ofmisalignment said first beam does not strike said photocell to asufficient degree to activate said photocell; and c) said photocellcommunicating with a signal system for said bridge such thatdeactivation of said photocell changes an output from said signal systemfrom indicating that said bridge is safe to cross to indicating thatsaid bridge is not safe to cross.
 14. The misalignment detection systemas in claim 13 in combination with a gauge for detecting the degree ofmisalignment between the fixed span and moveable span members of saidbridge; said gauge comprising:(a) an elongate bar; (b) a clamping basesecured to said elongate bar at a first end thereof for removablysecuring said elongate bar to a first of said fixed span and moveablespan members such that said elongate bar extends in parallel alignmentwith said member to which it is attached and a second end of saidelongate bar extends adjacent to the second of said members; (c) asecond source of collimated light removably mounted to said elongate barso as to direct a second beam of collimated light toward a second end ofsaid elongate bar; (d) a target holder having a target removablysecurable thereto; said target having a bulls-eye on a face thereof;said target holder slidably mounted to said second end of said elongatebar to permit said target holder to slide vertically and horizontallyrelative to said elongate bar and adapted to engage said second membersuch that said bulls-eye of said target mounted on the target holder isdisplaced relative to said second beam of collimated light an equivalentdistance, both vertically and horizontally, as the second member isdisplaced relative to the first member; and (e) a marker selectivelypositionable relative to said target face to indicate where said secondbeam of collimated light strikes said target face.
 15. A misalignmentdetection system for use in verifying whether a moveable span member ona moveable span of a bridge extends within an acceptable range ofmisalignment with a fixed span member on a fixed span of the bridge;said detection system comprising:a) a transmitter comprising a firstsource of collimated light and mounted on a first of said moveable spanand said fixed span of said bridge and positioned to direct a first beamof collimated light toward said second of said moveable span and saidfixed span; b) a receiver mounted on a second of said moveable span andsaid fixed span of said bridge and including a photo cell; said receiverand said transmitter mounted relative to said first and second membersand to each other such that when said first span and moveable spanmembers extend within the acceptable range of misalignment said firstbeam strikes said photo cell to a sufficient degree to activate saidphotocell, and when said fixed span and moveable members extend beyondthe acceptable range of misalignment said first beam does not strikesaid photocell to a sufficient degree to activate said photocell; c)said receiver includes a receiver aperture plate mounted in front ofsaid photocell and having a receiver aperture extending therethrough;said receiver aperture sized, shaped and positioned such that said firstbeam of collimated light will not strike said photocell to a sufficientdegree to activate said photocell unless said fixed span and moveablespan members are within the acceptable range of misalignment.
 16. Themisalignment detection system as in claim 15 wherein:a) said transmitterincludes a transmitter aperture plate mounted in front of a source of anon-collimated beam of light; said transmitter aperture plate having atransmitter aperture extending therethrough adapted to reduce divergenceof said non-collimated beam of light passing therethrough to producesaid first beam of collimated light.